Conveying apparatus



pril 27, 1954 K. J. sYLvEs'r CONVEYING APPARATUS Filed March 18, 1952 jw TI f7 f7 ATTORNEYS Patented Apr. 27, 1954 OONVEYING APPARATUS Karl Jens Sylvest, Copenhagen, Denmark, as-

signor to F. L. Smidth & Co., New York, N. Y., a corporation of New Jersey Application March l18, 1952, Serial No. 277,237

s Claims.V (o1. 3oz-29) This invention relates to apparatus vfor 'conveying granular and pulverulent materials, which;

includes a trough or a tube or other duct having an air-permeable diaphragm supporting the'l material frequently used is porous lter stone,

which is quite brittle, and, when such stones are employed, it is necessary to set them in special frames or to employ resilient packing with them.

The frames or packing are necessary in order to seal the side edges of the diaphragm and pre.- vent leakage of air by-passng the diaphragm and the frames or packing also protect the diaphragm against being broken during its installation. Canvas has been used as the diaphragm material, but, if the diaphragm .is made of only one or a few layers of canvas, a good seal requires the use of packing.

The present invention is directed to the provision of a novel diaphragm for use in conveying apparatus, which affords ra, number of ad vantages over those heretofore used for the purpose. The new diaphragm is sufficiently strong and rigid to carry the material being conveyed and, at the same time, is suilciently resilient, so that it can withstand without injury the clamping pressure, which must be applied along its side edges by the upper and lower parts of the conveyor structure to prevent escape of air-1- The use of the -new diafphragm thus does not require either special j around those edges.

frames or resilient packing. K

The essential element of the new diaphragm is a porous compressible body of unspun bres lying at random to one another and bound together either by means of a binder or by being felted. The bres may be of mineral, vegetable, or animal origin and the diaphragm may be made, for example, of plates of wood fibre, such as are commonly used for heat insulation. The plates may also be made of fibres of glass or mineral wool or asbestos held together by a binder, such as water glass or sorell cement,-

which is a mixture of magnesium chloride and magnesium oxides. Plates of the kinds men,

tioned may readily be made with the desired de- 2 I gree of porosity, which should be such that the pressure drop across such a plate is between 2" and 6" water gauge, when the amount of air passing through the plate varies from 3.5 to '7 cu. ft. of air per minute per square foot of area. The plates may be from 0.2 to 0.8 thick, but, if the plates are as thin as 0.2, it is advantageous to support them on perforated sheetmetal, so that they will properly carry the weight of the material being conveyed.

Felt made of interlocked animal bres is elastic enough to withstand clamping without injury and may be of the desired porosity. If the felt is suilciently thick, it may be used alone, but it is preferably provided with a support of openwork or perforated metal. protect one or both faces of the felt with a layer of canvas. A diaphragm comprising a sheet of felt may thus include a canvas layer covering the felt and protecting it against abrasion by the material being conveyed, a supporting network of metal, and a lower canvas layer between the under side of the felt and the network. The lower canvas layer not only protects the felt from damage by the netting but also makes it possible to use a felt of somewhat looser construction and greater porosity than would otherwise be suitable.

The upper surface of any of the fibrous daphragms described may be advantageously provided with a covering of openwork or perforatedmetal. Such a metal sheet checks the movement of the layer of material being conveyed, which lies closest to the diaphragm, and thus reduces abrasion of the upper surface of the diaphragm by the material. The metal sheet clamped at its edges between the upper and lower parts of; the conveyor structure also resists any tendency of the diaphragm to arch upward by reason of the pressure differentialacross the diaphragm and thus tends to maintain an even air distribution.

An example of a diaphragm with a support and a cover may consist of the following layers from top to bottom:

1. Netting made of 1 mm. wire with a mesh of 2. Sheet of 12oz. canvas.

3. Sheet of felt '7 mm. thick.

4. Sheet of 12 oz. canvas. y

5. Netting'made of 2mm. wire with a 10 mm.

mesh.

When such a diaphragmis used for the conveyance o f Portland cement in a trough inclinedA at 4 to the horizontal, a suitable ow of air is 5.25

It is also preferable to to 7 cu. ft. of air per min. per sq. ft. of diaphragm surface and this is accompanied by a pressure drop of 8"-10" water gauge across the diaphragm.

For a better understanding of the invention reference may be had to the accompanying drawing in which Fig. 1l is a'view in side elevationof a portion of a conveying :apparatusembodying the invention;

Figs. 2 and 3 are sectional views on the lines 2--2 and 3-3, respectively, of Fig. 1;

Fig. 4 is a vertical sectional view through the brous element of the new diaphragm;

Fig. 5 is a vertical sectional;.viewthrough a form of the diaphragm including-woven and` metallic sheets.

Fig. 6 is a plan view, with parts broken away, of the diaphragm shown in Figq;

Fig. '7 is a perspective view showing the manner of mounting the lower metallic member of the diaphragm; and

Fig. v8 is a fragmentary sectional view showing the manner of mounting the diaphragm lshow-n inFig. 5.

'Ihe apparatus shown in Fig. l comprises a duct IQ made up of a trough .II and a cover I2 of inverted trough shape, Awhich are provided, respectively, wi-th lateral flangesl 3, I4 secured together by bolts I5. The trough and cover are made up of sections provided, respectively, with end flanges I, I1 connected together by bolts I8, and the duet consists of the required number of trough and cover sections to produce a duct of the vdesired length. f i

The duct I0 is divided into two parts by a diaphragm I9whichfextends across theduc-t and has its edges clamped;betweerrflan'ges I?. and I4, the bolts I5 passing throughv openings in the diaphragm. The diaphragm comprises a porous compressible layer 2t :of unspunnfibres lying-in random distribution and `bound to one `another and the layermay-be a `plateof woo'dfibres, such as is commonly ernployedfor heat insulation, `or it may bemaderup of .iibres of glass or -mineral wool or asbestos bound by aA suitable binder. As an alternative, 'the layer .may be madefof knbres of animal origin bound vtogether by felting.v

The diaphragm may consist onlyoi the fibrous layer 20,-in which. event, ithe layer must be of substantial thickness ain 'order' to support the weight of the material being carried. Itis preferable to use a somewhat thinner layer vand to .give it yrigidity and'strength by .employing with .it an openworl: metal sheet 2I. The sheet ,may have a multiplicity of nneiperiorations or ,1ii preferred,I it may be a woven wire screen A22. When thesupporting metal sheet is employed, Vits `width .is less than the overall width of flanges 'I4 rof trough IzI and the upper surfaces of .the angesare-preferably countersunk, vas `indicated a's23,itoreceive the edges of the-sheet. The edgies'of thefs'h'eet lying on the flanges are then secured in place by spot-welding, as shown at '24. With? this arrangement, the compressiblelayer 2u makes contact with the faces of the flanges beyond the edges of the metallic sheet. l Y

In some cases, it may be desirable to provide the diaphragm with protective facings 25, of woven fabric. Such a facing may 4be .applied to either surface of the fibrous layer .I 9 and the fabric sheets serve di-ierent purposes vas follows: The upper sheet 25, with which the material being conveyed comes into contact, protects the fibrous layerfrom `abrasion by the material.A The 'lower fabric-'sheet 2S protects the librcuslayer against 4 damage by the metal sheet 22, when the latter is used, and also assists in controlling the rate of flow of air through the diaphragm, so that the fibrous body 20 may be of somewhat greater porosity than would otherwise be desirable.

It is also desirable in some instances to construct the diaphragm with an upper openwork metalfslieetfsiich as thescreen 21'. 'When such a screen is employed, itis of less width than the overall width of the anges I3 on the upper mem- -ber of the duct, and the flanges I3 are countersunk to receive the edges of the sheet 2. The edges ofthe sheet are then held in position by spot-welding, as indicated at 28. The sheet 21 resists the tendency of the diaphragm to bulge upwardly by reason of the differential pressure on -its oppositefaces and also tends to insure a uniform distribution of air. The metal sheet also checks the movement of the layer of material nearest the diaphragm l'and thus reduces the abrasive 'action-of the material;

'Ilhe diaphragm is :made-'up in sections and, at the places wheretheends vof r,adjacent fibrous layers 20 meet, the edges "may be covered 'by an impermeable vmetal strip 29, which extends across the duct andisnclamped at its "ends by the flanges I3, I4. The strip lshould be relatively narrow, so that the material will not be retarded in flowing over it. When Vthe `porous body 20 Vis made of felt, adjacent lengths of the felt may vbe secured together by scarfed or butt joints', the latter being glued. Joints in the fabricsheets can be made by slight overlapping and the imetalsheets may be either butted or slightly overlapped.

In the operation of 4the apparatus, air is supplied to thev interior of the trough I I `through inlets 3B spaced along the trough II andthe air passes upward through the'diaph'ragm and is diffused through the material 'lying 4thereon to render the materialuent. The duct is inclined sothat, when the material is fiuidized, it flows through the duct by gravity. The duct need not have a cover I2, ibut, if the cover is omitted, elements similar to flanges I3 are provided, so that the edges of the diaphragm can be clamped. The duct may be of `any desired cross-section and may be straight or curved;

All forms of the diaphragm described include the porous compressibleflayer 2U, which can be clamped directly between flanges I3, Is of the members of the duct Without the use of special frames or resilient packings. 'The clamping of the layer so compresses ther clamped portions thereof .as to seal them, with the result that air cannot escape through the edges of the diafphragm,l but "must Vilow'upwardly into the material lying thereon. Because Aof the compressibilityof the ydiaphragm structure, it is not subject to breakage when being vinstalled and, when used in-V `'an-Tuncovered trough,1there is no likelihood'of 'its being injured by a foreign object dropping into the trough.

l. In conveying apparatus having a trough with spaced ilat rtop surfaces and means supplying air under pressure to the interior oi" the trough, adiaphragrn"resting on said surfaces to close thetopr of the -troughand comprising a porous yielding'layerV oi unspun iibei'sbound together in random distribution within the layer and a -sheet'or vporous woven teXtilefabric covering and in :direct contact with one face of the layer.

V2. In conveying apparatus having a trough with -spacedfiat-topsuraces and means supplying air under pressure to the interior of the trough, a diaphragm resting on said surfaces to close the top of the trough and comprising a yielding porous layer of compressible unspun bers bound together in random distribution Within the layer, a sheet of woven textile fabric covering and in direct contact with a face of the layer and an openworl: metal sheet covering and in contact with the outer face of the sheet.

3. In conveying apparatus having a trough with spaced at top surfaces and means supply'- ing air under pressure to the interior of the trough, a diaphragm resting on said surfaces to close the top of the trough and comprising a layer of felt and a sheet of canvas covering and iii direct contact with one face of the layer.

4. In conveying apparatus having a trough with spaced flat top surfaces and means supplying air under pressure to the interior of the trough, a diaphragm resting on said surfaces to close the top of the trough and Comprising a layer of felt and sheets of canvas covering and in direct contact with the opposite faces of the layer.

5. In conveying apparatus having a trough with spaced iiat top surfaces and means supplying air under pressure to the interior of the trough, a diaphragm resting on said surfaces to close the top of the trough and comprising a layer of felt, a sheet of canvas covering and in direct contact With one surface of the felt and an openwork metal sheet covering and in direct contact with the outer surface of the canvas.

6. In conveying apparatus having a trough with spaced at top surfaces and means supplying air under pressure to the interior of the trough, a diaphragm resting on said surfaces to close the top of the trough and comprising a porous yielding layer of unspun bers bound together in random distribution within the layer and a sheet of porous Woven textile fabric covering and in direct contact with one face of the layer, said diaphragm having a gas-permeability such that the pressure drop thereacross is between two inches and six inches water gauge when the amount of air passing through the plate varies from 3.5 to 7 cu. ft. of air per minute per square foot of area,

References Cited in the le of this patent UNITED STATES PATENTS Number 

